System and method for dynamic cell selection and resource mapping for CoMP joint transmission

ABSTRACT

A wireless communication system includes a number of base stations capable of communicating with a plurality of subscriber stations. The base station coordinates transmission of resource blocks with a transmission of resource blocks from a second base station. The resource blocks include at least one reference signal (RS) patterns. In addition, base station punctures a plurality of resource elements in the resource blocks that might overlap with one of the CRS patterns in another resource block transmitted by the second base station such that no data is transmitted in the plurality of punctured resource elements. The subscriber station receives the resource blocks from at least two base stations and can avoid reading data from the resource elements that might overlap.

CROSS-REFERENCE TO RELATED APPLICATION(S) AND CLAIM OF PRIORITY

The present application is related to an application for reissue of U.S.Pat. No. 8,274,951 issued Sep. 25, 2012 on U.S. Non-Provisional patentapplication Ser. No. 12/716,144 filed Mar. 2, 2010, and claims thepriority to and the benefit under 35 U.S.C. § 119(e) of the filing dateof U.S. Provisional Patent Application No. 61/210,291, filed Mar. 17,2009, entitled “DYNAMIC CELL SELECTION FOR CoMP REPORTING SET ANDTRANSPARENT RESOURCE MAPPING FOR CoMP JP”. Provisional PatentApplication No. 61/210,291 is assigned to the assignee of the presentapplication and The content of the above-identified patent documents ishereby incorporated by reference into the present application as iffully set forth herein. The present application hereby claims priorityunder 35 U.S.C.§119(e) to U.S. Provisional Patent Application No.61/210,291.

TECHNICAL FIELD OF THE INVENTION

The present application relates generally to wireless communicationsand, more specifically, to dynamic cell selection and resource mappingin wireless communications networks.

BACKGROUND OF THE INVENTION

In a wireless communications network, multiple cells or base stations(also referred to as “eNBs”) use frequency bands and standardizedcodebooks for precoding transmission to their respective user equipments(UEs), using multiple transmit antennas. A typical problem of thisprocedure occurs where several cells or base stations are serving theirintended UEs while interfering with each other's signal. This scenariois called “inter-cell interference.” Inter-cell interference constrainsthe throughput of the wireless network.

SUMMARY OF THE INVENTION

A base station capable of communicating with a plurality of subscriberstations is provided. The base station includes a plurality of antennaconfigured to transmit data and control information and a transmittercoupled to the plurality of antenna. The transmitter is configured totransmit a plurality of symbols in a sub-frame to a subscriber station.The base station also includes a controller configured to include abitmap in a downlink control information (DCI). The bitmap is configuredto inform the subscriber station regarding a subset of cells within aCoMP measurement set for channel quality information reporting.

A subscriber station capable of communicating with a plurality of basestations is provided. The subscriber station includes a plurality ofantenna configured to receive data and control information and areceiver coupled to the plurality of antenna. The receiver is configuredto receive a plurality of symbols in a sub-frame from a base station.The subscriber station also includes a controller configured tointerpret a bitmap in a downlink control information (DCI). The bitmapis configured to identify a subset of cells within a CoMP measurementset for channel quality information reporting.

A method for communicating with a plurality of subscriber stations isprovided. The method includes transmitting, to a subscriber station, aplurality of symbols in a sub-frame and including a bitmap in a downlinkcontrol information (DCI). The bitmap is configured to inform thesubscriber station regarding a subset of cells within a CoMP measurementset for channel quality information reporting.

A base station capable of communicating with a plurality of subscriberstations is provided. The base station includes a plurality of antennaconfigured to transmit data and control information. The base stationalso includes a transmitter coupled to the plurality of antenna. Thetransmitter is configured to transmit a first resource block to asubscriber station. The base station further includes a controllerconfigured to coordinate transmission of the first resource block with atransmission of at least one additional resource block that istransmitted from at least one additional base station to the subscriberstation. The transmissions of the first and at least one additionalresource blocks are coordinated such that the subscriber stationreceives single resource block that comprises at least one of the firstand the at least one additional resource block. The first and at leastone additional resource blocks include at least one reference signal(RS) pattern. The controller is configured to puncture a plurality ofresource elements in the first resource block that might overlap withone of the RS patterns in one or more of the additional resourceblock(s) such that no data is transmitted in the plurality of puncturedresource elements.

A subscriber station capable of communicating with a plurality of basestations is provided. The subscriber station includes a plurality ofantenna configured to receive data and control information and areceiver coupled to the plurality of antenna. The receiver is configuredto receive a single resource block. The single resource block includesat least one of: a first resource block received from a first basestation; and at least one additional resource block received from atleast one additional base station. The first and at least one additionalresource blocks include at least one reference signal (RS) pattern. Thereceiver is configured to not expect data in a plurality of puncturedresource elements in the first resource block that might overlap withone of the at least one RS pattern in one or more of the at least oneadditional resource block.

A method for communicating with a plurality of subscriber stations isprovided. The method includes transmitting a first resource block to asubscriber station and coordinating the transmission of the firstresource block with a transmission of at least one additional resourceblock from at least one additional base station to the subscriberstation such that the subscriber station receives single resource blockthat includes at least one of the first and the at least one additionalresource block. The first and at least one additional resource blockscomprise at least one reference signal (RS) patterns. The method alsoincludes puncturing a plurality of resource elements in the firstresource block that might overlap with one of the at least one RSpatterns in the at least one additional resource block such that no datais transmitted in the plurality of resource elements in the firstresource block that might overlap with one of the at least one RSpatterns in the at least one additional resource block.

Before undertaking the DETAILED DESCRIPTION OF THE INVENTION below, itmay be advantageous to set forth definitions of certain words andphrases used throughout this patent document: the terms “include” and“comprise,” as well as derivatives thereof, mean inclusion withoutlimitation; the term “or,” is inclusive, meaning and/or; the phrases“associated with” and “associated therewith,” as well as derivativesthereof, may mean to include, be included within, interconnect with,contain, be contained within, connect to or with, couple to or with, becommunicable with, cooperate with, interleave, juxtapose, be proximateto, be bound to or with, have, have a property of, or the like; and theterm “controller” means any device, system or part thereof that controlsat least one operation, such a device may be implemented in hardware,firmware or software, or some combination of at least two of the same.It should be noted that the functionality associated with any particularcontroller may be centralized or distributed, whether locally orremotely. Definitions for certain words and phrases are providedthroughout this patent document, those of ordinary skill in the artshould understand that in many, if not most instances, such definitionsapply to prior, as well as future uses of such defined words andphrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1A illustrates exemplary wireless network 100 that is capable ofdecoding data streams according to an exemplary embodiment of thedisclosure;

FIG. 1B illustrates a joint transmission in a wireless network accordingembodiments of the present disclosure;

FIG. 1C illustrates CMCS, CRCS and Active CoMP Sets according toembodiments of the present disclosure;

FIG. 2 illustrates exemplary base station in greater detail according toembodiments of the present disclosure;

FIG. 3 illustrates an exemplary wireless mobile station according toembodiments of the present disclosure;

FIGS. 4 and 6 illustrate an uplink scheduling grant for CoMPtransmissions according to embodiments of the present disclosure;

FIG. 5 illustrates a process for network configuration of CoMP setsaccording to embodiments of the present disclosure;

FIGS. 7 through 11 illustrate CoMP PDSCH resource mapping according toembodiments of the present disclosure;

FIGS. 12 and 14 illustrate frequency shifts for CRS according toembodiments of the present disclosure; and

FIGS. 13 and 15 illustrate a resource element mapping of CoMP PDSCHbased on overlapping patterns according to embodiments of the presentdisclosure.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 through 15, discussed below, and the various embodiments used todescribe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged wireless communication system.

With regard to the following description, it is noted that the LTE term“node B” is another term for “base station” used below. Further, theterm “cell” is a logic concept that can represent a “base station” or a“sector” belongs to a “base station”. In the present disclosure, “cell”and “base station” are used interchangeably to indicate the actualtransmission units (may be “sector” or “base station” and the like) inthe wireless system. Also, the LTE term “user equipment” or “UE” isanother term for “subscriber station” used below.

With regard to the following description, it is noted that thediscussion is focused on reference signals (RS) including commonreference signals (CRS), channel state information reference signals(CSI-RS), and the like. The collision between CRS and PDSCH discussed inthe document is for illustration purpose, however, the collision betweenreference signal resource elements and PDSCH resource elements willoccur for any type of reference signals.

FIG. 1A illustrates exemplary wireless network 100 that is capable ofdecoding data streams according to one embodiment of the presentdisclosure. In the illustrated embodiment, wireless network 100 includesbase station (BS) 101, base station (BS) 102, and base station (BS) 103.Base station 101 communicates with base station 102 and base station103. Base station 101 also communicates with Internet protocol (IP)network 130, such as the Internet, a proprietary IP network, or otherdata network.

Base station 102 provides wireless broadband access to network 130, viabase station 101, to a first plurality of subscriber stations withincoverage area 120 of base station 102. The first plurality of subscriberstations includes subscriber station (SS) 111, subscriber station (SS)112, subscriber station (SS) 113, subscriber station (SS) 114,subscriber station (SS) 115 and subscriber station (SS) 116. Subscriberstation (SS) may be any wireless communication device, such as, but notlimited to, a mobile phone, mobile PDA and any mobile station (MS). Inan exemplary embodiment, SS 111 may be located in a small business (SB),SS 112 may be located in an enterprise (E), SS 113 may be located in aWiFi hotspot (HS), SS 114 may be located in a residence, SS 115 may be amobile (M) device, and SS 116 may be a mobile (M) device.

Base station 103 provides wireless broadband access to network 130, viabase station 101, to a second plurality of subscriber stations withincoverage area 125 of base station 103. The second plurality ofsubscriber stations includes subscriber station 115 and subscriberstation 116. In alternate embodiments, base stations 102 and 103 may beconnected directly to the Internet or other controller unit by means ofa wired broadband connection, such as an optical fiber, DSL, cable orT1/E1 line, rather than indirectly through base station 101.

In other embodiments, base station 101 may be in communication witheither fewer or more base stations. Furthermore, while only sixsubscriber stations are shown in FIG. 1A, it is understood that wirelessnetwork 100 may provide wireless broadband access to more than sixsubscriber stations. It is noted that subscriber station 115 andsubscriber station 116 are on the edge of both coverage area 120 andcoverage area 125. Subscriber station 115 and subscriber station 116each communicate with both base station 102 and base station 103 and maybe said to be cell-edge devices interfering with each other. Forexample, the communications between BS 102 and SS 116 may be interferingwith the communications between BS 103 and SS 115. Additionally, thecommunications between BS 103 and SS 115 may be interfering with thecommunications between BS 102 and SS 116.

In an exemplary embodiment, base stations 101-103 may communicate witheach other and with subscriber stations 111-116 using an IEEE-802.16wireless metropolitan area network standard, such as, for example, anIEEE-802.16e standard. In another embodiment, however, a differentwireless protocol may be employed, such as, for example, a HIPERMANwireless metropolitan area network standard. Base station 101 maycommunicate through direct line-of-sight or non-line-of-sight with basestation 102 and base station 103, depending on the technology used forthe wireless backhaul. Base station 102 and base station 103 may eachcommunicate through non-line-of-sight with subscriber stations 111-116using OFDM and/or OFDMA techniques.

Base station 102 may provide a T1 level service to subscriber station112 associated with the enterprise and a fractional T1 level service tosubscriber station 111 associated with the small business. Base station102 may provide wireless backhaul for subscriber station 113 associatedwith the WiFi hotspot, which may be located in an airport, café, hotel,or college campus. Base station 102 may provide digital subscriber line(DSL) level service to subscriber stations 114, 115 and 116.

Subscriber stations 111-116 may use the broadband access to network 130to access voice, data, video, video teleconferencing, and/or otherbroadband services. In an exemplary embodiment, one or more ofsubscriber stations 111-116 may be associated with an access point (AP)of a WiFi WLAN. Subscriber station 116 may be any of a number of mobiledevices, including a wireless-enabled laptop computer, personal dataassistant, notebook, handheld device, or other wireless-enabled device.Subscriber station 114 may be, for example, a wireless-enabled personalcomputer, a laptop computer, a gateway, or another device.

Dotted lines show the approximate extents of coverage areas 120 and 125,which are shown as approximately circular for the purposes ofillustration and explanation only. It should be clearly understood thatthe coverage areas associated with base stations, for example, coverageareas 120 and 125, may have other shapes, including irregular shapes,depending upon the configuration of the base stations and variations inthe radio environment associated with natural and man-made obstructions.

Also, the coverage areas associated with base stations are not constantover time and may be dynamic (expanding or contracting or changingshape) based on changing transmission power levels of the base stationand/or the subscriber stations, weather conditions, and other factors.In an embodiment, the radius of the coverage areas of the base stations,for example, coverage areas 120 and 125 of base stations 102 and 103,may extend in the range from less than 2 kilometers to about fiftykilometers from the base stations.

As is well known in the art, a base station, such as base station 101,102, or 103, may employ directional antennas to support a plurality ofsectors within the coverage area. In FIG. 1, base stations 102 and 103are depicted approximately in the center of coverage areas 120 and 125,respectively. In other embodiments, the use of directional antennas maylocate the base station near the edge of the coverage area, for example,at the point of a cone-shaped or pear-shaped coverage area.

The connection to network 130 from base station 101 may comprise abroadband connection, for example, a fiber optic line, to serverslocated in a central office or another operating companypoint-of-presence. The servers may provide communication to an Internetgateway for internet protocol-based communications and to a publicswitched telephone network gateway for voice-based communications. Inthe case of voice-based communications in the form of voice-over-IP(VoIP), the traffic may be forwarded directly to the Internet gatewayinstead of the PSTN gateway. The servers, Internet gateway, and publicswitched telephone network gateway are not shown in FIG. 1A. In anotherembodiment, the connection to network 130 may be provided by differentnetwork nodes and equipment.

In accordance with an embodiment of the present disclosure, one or moreof base stations 101-103 and/or one or more of subscriber stations111-116 comprises a receiver that is operable to decode a plurality ofdata streams received as a combined data stream from a plurality oftransmit antennas using an MMSE-SIC algorithm. As described in moredetail below, the receiver is operable to determine a decoding order forthe data streams based on a decoding prediction metric for each datastream that is calculated based on a strength-related characteristic ofthe data stream. Thus, in general, the receiver is able to decode thestrongest data stream first, followed by the next strongest data stream,and so on. As a result, the decoding performance of the receiver isimproved as compared to a receiver that decodes streams in a random orpre-determined order without being as complex as a receiver thatsearches all possible decoding orders to find the optimum order.

FIG. 1B illustrates a joint transmission in a wireless network 100according embodiments of the present disclosure. Base station (BS) 102(e.g., “Cell 1”) and BS 103 (e.g., “Cell 2”) are performing acoordinated multipoint (CoMP) transmission to the subscriber station(SS) 116, that is, communications to and from SS 116 are conductedthrough BS 102 and BS 103. H_(i1) corresponds to the wireless channelfrom “Cell i” to SS 116. Accordingly, H₁₁ 135 corresponds to thewireless channel from BS 102 to SS 116; and H₂₁ 140 corresponds to thewireless channel from BS 103 to SS 116. When in the joint processingmode, BS 102 and BS 103 jointly process SS 116's information together.BS 102 and BS 103 send SS 116's information over the air to SS 116substantially simultaneously through the wireless channels. By doingthis, the interference is greatly reduced while the received power (sumfrom the two cells BS 102 and BS 103) is greatly improved. Illustrationof two cells, BS 102 and BS 103 is for example purposes only and otherembodiments including more than two cells could be used withoutdeparting from the scope of this disclosure.

CoMP transmission can be classified into two categories: coordinatedscheduling and/or beam-forming, and CoMP joint transmission. Incoordinated scheduling and/or beam-forming, data to SS 116 istransmitted from BS 102 while the scheduling decisions are coordinatedto control the interference generated in a set of coordinated cells. Inother words, the data intended for SS 116 is not shared while someinformation related to the channels and the controls are shared amongdifferent cells. The signals received from other cells or base stationsare treated as inter-cell interference and are avoided in the spatial,frequency or time domain. Alternatively, in the class of jointprocessing and joint transmission, data to SS 116 is substantiallysimultaneously transmitted from multiple transmission points to improvethe received signal quality and/or cancel activity interference forother subscriber stations. Data intended for a particular SS 116 isshared among different cells, such as between BS 102 and BS 103, and isjointly processed at these cells. As a result of this joint processing,the received signals at SS 116 will be coherently or non-coherentlyadded up together. The signals received from other cells or basestations are treated as useful signals that contribute to a much higherreceived SNR at SS 116. Within this mode of operation, the two classesof transmission schemes are: CoMP SU-MIMO and CoMP For CoMP SU-MIMO, theCoMP joint transmission can increase both the average cell throughputtogether with the cell-edge user throughput.

SS 116 can receive signals H₁₁ 135 from BS 102 and signals H₂₁ 140 fromBS 103 respectively. SS 116 superimposes the signals with each otherinstead of treating one of the signals as interfering. For example, BS102 includes a number, N_(T1), of transmit antenna. Additionally, SS 116includes a number, N_(R), of receive antennas. The received signal at SS116 can be represented by Equation 1:Y₁=H₁₁w₁X₁+H₂₁w₂X₁+N₁   [Eqn. 1].

In Equation 1, H₁₁ 135 and H₂₁ 140 represent the respective channelgains from BS 102 and BS 103 to SS 116. Additionally, Y₁ is the N_(R)×1vector of received signal at SS 116, X₁ is the intended message for SS116, w_(i) is the N_(T1)×v precoding vector of transmitted signal at BS102, and N_(i) is the N_(R)×1 AWGN noise vector. Further, v is thenumber of transmission layers of signal X₁.

FIG. 1C illustrates CMCS, CRCS and Active CoMP Sets according toembodiments of the present disclosure. The embodiment shown in FIG. 1Cis for illustration only. Other embodiments could be used withoutdeparting from the scope of this disclosure.

In order to perform the CoMP joint processing operation, the networkdecides which set of cells will be transmitting to a particular CoMP UE(e.g., CoMP subscriber station) and what the related channel informationis. In some embodiments, there exist several CoMP sets. The networkfirst configures a set of cells (“CoMP measurement cell set (CMCS)”) tobe measured by CoMP subscriber stations. The CMCS 145 is a set of cellsmonitored, measured, and reported by the CoMP UE. The CMCS 145 isconfigured semi-statically and can be completely determined by thenetwork or be determined by the network with the assistant from CoMPUEs. Based on the measurements on the “CMCS” 145, the network will thenconfigure another set of cells (“CoMP reporting cell set (CRCS) 150”) tobe the set of cells that CoMP UEs should report the information relatedto channel knowledge (channel coefficients, precoding matrix indices,channel quality indices and so forth). This CRCS 150 can be configuredby the network with the assistance of the CoMP UEs. In some embodiments,to enable this procedure SS 116 can feedback a received SINR or anindication of preference. After obtaining the channel relatedinformation, the network decides the “Active CoMP set” 155 (the set ofcells which send CoMP PDSCH to the CoMP UE) and performs the CoMP jointprocessing. That is, the network determines which set of cells, referredto as the Active CoMP set 155, will transmit to the CoMP UE.

The configuration of the CRCS 150 can be semi-statistic and subscriberstation-specific. The configuration of the CRCS 150 and can be importantfor the uplink overhead since the UL channel quality reporting of SS116, when a CoMP subscriber station, is tied to this set. In someembodiments, the reporting within the CRCS 150 is dynamic. Since theCRCS 150 can be relatively large, such as three (3) cells or more, if SS116 reports channel related information for all the cells within theCRCS 150 all the time, the overhead can be very large. Furthermore,since demodulation of CoMP PDSCH will be based on DRS, R1-091066, “Wayforward on downlink reference signals for LTE-A”, the contents of whichhereby are incorporated by reference, the network can be free to decidethe active CoMP set 155. Therefore, if the network decides to use fewertransmission points within the CRCS 150, the network only needs to knowchannel related information for a subset of the CRCS 150. The dynamicchannel feedback reporting will then significantly reduce the feedbackoverhead.

In CoMP joint processing, a collision between CoMP PDSCH and referencesignals (RS) including common reference signals (CRS) from differentcells may occur. This problem can occur where cell-specificfrequency/time shifts are used for the reference signals in the cellsinvolved in the joint transmission and, at the same time, the PDSCHmapping is assumed to be the same in all the cells. In general, thisissue exists for non-CoMP subscriber stations when their PDSCH collideswith reference signals from other cells. However, CoMP subscriberstations can be more susceptible to this type of PDSCH-to-RSinterference because the PDSCH received is assumed to be coherentlycombined over the air.

The demodulation of CoMP PDSCH can be based on DRS to enable transparenttransmission between SS 116 and the active CoMP set. That is, SS 116, asa CoMP subscriber station, should not be aware of the active CoMP set.

FIG. 2 illustrates an exemplary base station in greater detail accordingto one embodiment of the present disclosure. The embodiment of basestation 102 illustrated in FIG. 2 is for illustration only. Otherembodiments of the base station 102 could be used without departing fromthe scope of this disclosure.

Base station 102 comprises base station controller (BSC) 210 and basetransceiver subsystem (BTS) 220. A base station controller is a devicethat manages wireless communications resources, including the basetransceiver subsystems, for specified cells within a wirelesscommunications network. A base transceiver subsystem comprises the RFtransceivers, antennas, and other electrical equipment located in eachcell site. This equipment may include air conditioning units, heatingunits, electrical supplies, telephone line interfaces and RFtransmitters and RF receivers. For the purpose of simplicity and clarityin explaining the operation of the present disclosure, the basetransceiver subsystems in each of cells 121, 122 and 123 and the basestation controller associated with each base transceiver subsystem arecollectively represented by BS 101, BS 102 and BS 103, respectively.

BSC 210 manages the resources in cell site 121, including BTS 220. BTS220 comprises BTS controller 225, channel controller 235, transceiverinterface (IF) 245, RF transceiver unit 250, and antenna array 255.Channel controller 235 comprises a plurality of channel elements,including exemplary channel element 240. BTS 220 also comprises a memory260. The embodiment memory 260 included within BTS 220 is forillustration only. Memory 260 can be located in other portions of BS 102without departing from the scope of this disclosure.

BTS controller 225 comprises processing circuitry and memory capable ofexecuting an operating program that communicates with BSC 210 andcontrols the overall operation of BTS 220. Under normal conditions, BTScontroller 225 directs the operation of channel controller 235, whichcontains a number of channel elements, including channel element 240,that perform bi-directional communications in the forward channels andthe reverse channels. A forward channel refers to a channel in whichsignals are transmitted from the base station to the mobile station(also referred to as DOWNLINK communications). A reverse channel refersto a channel in which signals are transmitted from the mobile station tothe base station (also referred to as UPLINK communications). In anadvantageous embodiment of the present disclosure, the channel elementscommunicate according to an OFDMA protocol with the mobile stations incell 120. Transceiver IF 245 transfers the bi-directional channelsignals between channel controller 240 and RF transceiver unit 250. Theembodiment of RF transceiver unit 250 as a single device is forillustration only. RF transceiver unit 250 can separate transmitter andreceiver devices without departing from the scope of this disclosure.

Antenna array 255 transmits forward channel signals received from RFtransceiver unit 250 to mobile stations in the coverage area of BS 102.Antenna array 255 also sends to transceiver 250 reverse channel signalsreceived from mobile stations in the coverage area of BS 102. In someembodiments of the present disclosure, antenna array 255 is amulti-sector antenna, such as a three-sector antenna in which eachantenna sector is responsible for transmitting and receiving in a 120°arc of coverage area. Additionally, RF transceiver 250 may contain anantenna selection unit to select among different antennas in antennaarray 255 during transmit and receive operations.

According to some embodiments of the present disclosure, BTS controller225 is operable to execute programs, such as an operating system (OS)and processes for CoMP reporting and transparent resource mapping,stored in a memory 260. Memory 260 can be any computer readable medium,for example, the memory 260 can be any electronic, magnetic,electromagnetic, optical, electro-optical, electro-mechanical, and/orother physical device that can contain, store, communicate, propagate,or transmit a computer program, software, firmware, or data for use bythe microprocessor or other computer-related system or method. Memory260 comprises a random access memory (RAM) and another part of memory260 comprises a Flash memory, which acts as a read-only memory (ROM).

BSC 210 is operable to maintain communications between BS 102 and BS 101and BS 103. BS 102 communicates to BS 101 and BS 103 via the wirelessconnection 131. In some embodiments, the wireless connection 131 iswire-line connection.

FIG. 3 illustrates an exemplary wireless subscriber station according toembodiments of the present disclosure. The embodiment of wirelesssubscriber station 116 illustrated in FIG. 3 is for illustration only.Other embodiments of the wireless subscriber station 116 could be usedwithout departing from the scope of this disclosure.

Wireless subscriber station 116 comprises antenna 305, radio frequency(RF) transceiver 310, transmit (TX) processing circuitry 315, microphone320, and receive (RX) processing circuitry 325. SS 116 also comprisesspeaker 330, main processor 340, input/output (I/O) interface (IF) 345,keypad 350, display 355, and memory 360. Memory 360 further comprisesbasic operating system (OS) program 361 and applications for CoMPreporting and transparent resource mapping 362.

Radio frequency (RF) transceiver 310 receives from antenna 305 anincoming RF signal transmitted by a base station of wireless network100. Radio frequency (RF) transceiver 310 down-converts the incoming RFsignal to produce an intermediate frequency (IF) or a baseband signal.The IF or baseband signal is sent to receiver (RX) processing circuitry325 that produces a processed baseband signal by filtering, decoding,and/or digitizing the baseband or IF signal. Receiver (RX) processingcircuitry 325 transmits the processed baseband signal to speaker 330(i.e., voice data) or to main processor 340 for further processing(e.g., web browsing).

Transmitter (TX) processing circuitry 315 receives analog or digitalvoice data from microphone 320 or other outgoing baseband data (e.g.,web data, e-mail, interactive video game data) from main processor 340.Transmitter (TX) processing circuitry 315 encodes, multiplexes, and/ordigitizes the outgoing baseband data to produce a processed baseband orIF signal. Radio frequency (RF) transceiver 310 receives the outgoingprocessed baseband or IF signal from transmitter (TX) processingcircuitry 315. Radio frequency (RF) transceiver 310 up-converts thebaseband or IF signal to a radio frequency (RF) signal that istransmitted via antenna 305.

In some embodiments of the present disclosure, main processor 340 is amicroprocessor or microcontroller. Memory 360 is coupled to mainprocessor 340. According to some embodiments of the present disclosure,part of memory 360 comprises a random access memory (RAM) and anotherpart of memory 360 comprises a Flash memory, which acts as a read-onlymemory (ROM).

Main processor 340 executes basic operating system (OS) program 361stored in memory 360 in order to control the overall operation ofwireless subscriber station 116. In one such operation, main processor340 controls the reception of forward channel signals and thetransmission of reverse channel signals by radio frequency (RF)transceiver 310, receiver (RX) processing circuitry 325, and transmitter(TX) processing circuitry 315, in accordance with well-known principles.

Main processor 340 is capable of executing other processes and programsresident in memory 360. Main processor 340 can move data into or out ofmemory 360, as required by an executing process. In some embodiments,the main processor 340 is configured execute programs, such as OS 361and processes for CoMP reporting and transparent resource mapping 362.The main processor 340 can execute the CoMP reporting and transparentresource mapping 362 based on OS program 361 or in response to a signalreceived from BS 102. Main processor 340 is also coupled to I/Ointerface 345. I/O interface 345 provides subscriber station 116 withthe ability to connect to other devices such as laptop computers andhandheld computers. I/O interface 345 is the communication path betweenthese accessories and main controller 340.

Main processor 340 is also coupled to keypad 350 and display unit 355.The operator of subscriber station 116 uses keypad 350 to enter datainto subscriber station 116. Display 355 may be a liquid crystal displaycapable of rendering text and/or at least limited graphics from websites. Alternate embodiments may use other types of displays.

In some embodiments, the network first configures, via higher layersignaling, a set of cells, i.e., the CMCS 145, to be measured by CoMPUEs, i.e., SS 116. After obtaining a feedback from SS 116, the networksemi-statistically configures, via higher layer signaling, a second setof cells, i.e., the CRCS 150, to be the set of cells to which SS 116reports information related to the channel.

FIG. 4 illustrates an uplink scheduling grant for CoMP transmissionsaccording to embodiments of the present disclosure. The embodiment ofthe scheduling grant 400 shown in FIG. 4 is for illustration only. Otherembodiments could be used without departing from the scope of thisdisclosure.

In some embodiments, the network dynamically assigns channel informationrelated reports, such as a channel quality index (CQI) report, withinthe CRCS 150. Additionally, the reporting set, CRCS 150, may not be usedsince the measurement set, CMCS 145, can be used to serve as thereporting set (that is, the measurement set and the reporting set can bemerged into the measurement set). The uplink scheduling grant 400includes a bitmap 408 included in a new downlink control information(DCI) format. The bits 410, 412, 414 indicate the cells to be reportedby SS 116 on the channel related information through the CQI report. Thecell IDs of these cells are available at SS 116. For example, the firstbit 410 corresponds to BS 102, the second bit 412 corresponds to BS 103and the third bit 414 corresponds to BS 101. The default ordering of thecells within the CRCS 150 can be in increasing order of the cell IDs orin decreasing order of the cell IDs. For each bit 410, 412, 414, “0” canindicate that the corresponding cell, such as BS 102, is needed forchannel information related feedback report, such as the CQI report andvice versa.

For example, using the uplink scheduling grant 400 with the new DCIformat shown in FIG. 4, it is indicated to SS 116 that SS 116 needs tofeedback channel related information concerning BS 102 (Cell 0) and BS101 (Cell 2) during the CQI report process. The ordering of the cells inthe bitmap 408 can be in the increasing order of the cell IDs,decreasing order or any other predetermined order. In the bitmap 408 allthe cells or base stations within the CRCS 150 will be indicated by thebitmap 408. The overall process can be illustrated with respect to FIG.5.

FIG. 5 illustrates a process for network configuration of CoMP setsaccording to embodiments of the present disclosure. The embodiment shownin FIG. 5 is for illustration only. Other embodiments could be usedwithout departing from the scope of this disclosure.

The network 505 configures 510 the CMCS 145 for SS 116 via higher layersignaling. The network 505 can configure 510 the CMCS 145 to SS 116through a radio resource control (RRC) configuration. Then, SS 116 knowswhich cells are included in the CMCS 145. Thereafter, SS 116 transmits ameasurement report 515 regarding each of the cells included in the CMCS145. The network 505 configures 520 the CRCS 150. The CRCS 150 can beconfigured as a periodic CQI. The network 505 then configures 525 asubset of the CRCS 150 to be the set of cells regarding which SS 116should report the information related to channel knowledge. The subsetof the CRCS 150 can be an aperiodic CQI report. Accordingly, SS 116 candown-select, from the CMCS 145 and CRCS 150, the cells under review. Forexample, SS 116 can perform aperiodic CQI reporting of the subset of thecells included in the CRCS 150.

FIG. 6 illustrates another uplink scheduling grant for CoMPtransmissions according to embodiments of the present disclosure. Theembodiment of the scheduling grant 600 shown in FIG. 6 is forillustration only. Other embodiments could be used without departingfrom the scope of this disclosure.

In some embodiments, the bitmap 608 only indicates the cells or basestations, other than the anchor cell, within the CRCS. In this setup, SS116 always reports channel related information concerning BS 102 (theanchor cell) during the CQI report process. For example, when BS 102(Cell 0) is the anchor cell, only two (2) bits of the bitmap 608 areneeded to indicate the other cells, BS 101 and BS 103, within the CoMPset. The mapping can be in increasing order of the cell ID, indecreasing order of the cell ID or another predetermined order asconfigured by higher layer. For example, SS 116 can include a bitmaptable, such as Table 1 below, stored in memory 360. SS 116 can interpretthe bitmap 608 according to Table 1.

TABLE 1 Bitmap of Cell Selection for CQI reporting Reporting Cells ofthe CQI Bit in the field Report Process [0 0] Cell 0 [0 1] Cell 0 andCell 2 [1 0] Cell 0 and Cell 1 [1 1] Cell 0, Cell 1, and Cell 2

For example, when the bitmap is “1 0”, SS 116 reports channel relatedinformation for BS 102 (the anchor cell, cell 0) and BS 103 (cell 1).

In some embodiments, the PDSCH is transmitted only in the resourceelements that will not overlap with any of the possible referencesignals, such as one or more CRSs. In this way, the PDSCH transmissionof CoMP joint processing can be transparent in the sense that the SS 116does not need to know the actual “active CoMP set”. SS 116 may notexpect to receive a CoMP PDSCH from the resource elements that have thepossibility of colliding with CRS from other cells.

FIG. 7 illustrates CoMP PDSCH resource mapping according to embodimentsof the present disclosure. The embodiment of the CoMP PDSCH resourcemaps 700, 701 shown in FIG. 7 is for illustration only. Otherembodiments could be used without departing from the scope of thisdisclosure.

For example, for the case where four CRSs are configured for each cellwithin the active CoMP set 155, the control region 705 for the CoMPjoint processing is sent in the first three OFDM symbols 721, 722, 723while the CoMP PDSCH region starts from the fourth OFDM symbol 724 inone subframe. The CoMP PDSCH Mapping includes a CoMP PDSCH Map 700 forBS 102 (the anchor cell, i.e., cell 0) and a CoMP PDSCH Map 701 for BS103 (cell 1). In each CoMP PDSCH resource map 700, 701, R denotes adownlink reference signal such that R₀, R₁, R₂ and R₃ are the commonreference symbols. It will be understood that R is not limited to acommon reference signal and that R can refer to any reference signalwithout departing from the scope of this disclosure. The shaded resourceelements (REs) 710 are the REs where a CRS-PDSCH collision can occur.Therefore, the shaded REs 710 are punctured and, thus, not used fortransmitting CoMP PDSCH (data) 715. As such, SS 116 is not expecting toreceive data from the second 722, fifth 725, eighth 728, ninth 729 andtwelfth 732 OFDM symbols in a normal CP subframe. When an RE ispunctured, such as by the BS, no data or reference symbol is transmittedin that RE. Puncturing the shaded REs 710 enables a reference symbol,such as the CRS, to be received stronger than if data 715 is transmittedin the shaded REs 710.

In another example, illustrated in FIG. 8, two CRSs, R₀ and R₁, areconfigured for each cell within the active CoMP set 155. In the CoMPPDSCH resource map 800 for BS 102 (the anchor cell, cell 0) and the CoMPPDSCH resource amp 801 for BS 103 (cell 1), the CoMP PDSCH region startsfrom the fourth OFDM symbols 824 in one subframe. The shaded resourceelements (REs) 810 are the REs where a CRS-PDSCH collision can occur.Accordingly, the shaded REs 810 are punctured such that SS 116 is notexpecting to receive data 815 from the fifth 825, eighth 828 and twelfth832 OFDM symbols.

In some embodiments, the CoMP PDSCH resource mapping is performedaccording to the cell-specific shifts of the cell IDs of the CRCS. Asshown in FIG. 1C, SS 116 (i.e., the CoMP UE) will be required to reportchannel related information to the cells in the CRCS 150 during the CQIreport process; therefore, the Cell IDs of the cells within CRCS 150will be available at the CoMP UEs, such as SS 116. Under this situation,SS 116 does not expect to receive data from resource elements that willoverlap with any of the possible CRSs within the CRCS 150.

In 3GPP TS36.211. v8.5.0. “EUTRA: Physical Channels and Modulation”, thecontents of which are incorporated by reference, the cell-specificfrequency shift is given by

v_(shift) = N_(ID)^(cell)mod 6.Assume the cell IDs of the cells in the CRCS are

N_(ID 1)^(cell), N_(ID 2)^(cell)and

N_(ID 3)^(cell),the set of possible cell-specific frequency shift can be illustrated byEquation 2:

$\begin{matrix}{v_{shift} = \left\{ {v_{i},{i = 1},2,{3{\left. {v_{i} = {N_{{ID}\; i}^{cell}{mod}\; 6}} \right\}.}}} \right.} & \left\lbrack {{Eqn}.\mspace{14mu} 2} \right\rbrack\end{matrix}$Then, SS 116 does not expect to receive CoMP PDSCH from the positions ofthe CRS resource elements of the described frequency shifts.

FIG. 9 illustrates CoMP PDSCH Resource Mapping Based on CRCS1 accordingto embodiments of the present disclosure. For example, if the CRCS1includes three cells, in which the cells IDs are ‘0’ for BS 102, ‘2’ forBS 101 and ‘6’ for another BS. Then the CoMP PDSCH resource mapping canbe as shown in FIG. 9 for the case of two CRSs, R₀ and R₁,configuration. The CoMP PDSCH Mapping includes a CoMP PDSCH Map 900 forBS 102 (the anchor cell, i.e., cell 0), a CoMP PDSCH Map 901 for BS 103(cell 1), and a CoMP PDSCH Map 902 for the cell 6 BS. In each of theCoMP PDSCH Maps 900, 901, 902, the control region 905 for the CoMP jointprocessing is sent in the first three OFDM symbols 921, 922, and 923while the CoMP PDSCH region starts from the fourth OFDM symbol 924. Theshaded resource elements (REs) 910 are the REs in which a CRS-PDSCHcollision can occur. Therefore the shaded REs 910 are punctured and arethe REs in which SS 116 does not expect to receive data 915.

FIG. 10 illustrates another example of CoMP PDSCH resource mappingaccording to this disclosure. In FIG. 10, a CRCS2 is utilized for thecase of two CRSs, R₀ and R₁, configuration. The CRCS2 includes threecells in which the cells IDs are ‘0’ for BS 102, ‘2’ for BS 101 and ‘6’for another BS. The CoMP PDSCH Mapping includes a CoMP PDSCH Map 1000for BS 102 (the anchor cell, i.e., cell 0), a CoMP PDSCH Map 1002 for BS101 (cell 2), and a CoMP PDSCH Map 1003 for the cell 6 BS. In each ofthe CoMP PDSCH Maps 1000, 1002, 1003, the control region 1005 for theCoMP joint processing is sent in the first three OFDM symbols 1021,1022, and 1023 while the CoMP PDSCH region starts from the fourth OFDMsymbol 1024. The shaded resource elements (REs) 1010 are the REs inwhich a CRS-PDSCH collision can occur. Therefore the shaded REs 1010that are punctured and are the REs in which SS 116 does not expect toreceive data 1015.

FIG. 11 illustrates another example of CoMP PDSCH resource mappingaccording to this disclosure. In FIG. 11, a CRCS3 is utilized for thecase of two CRSs, R₀ and R₁, configuration. The CRCS3 includes threecells in which the cells IDs are ‘0’ for BS 102, ‘6’ for another BS and‘12’ for yet another BS. The CoMP PDSCH Mapping includes a CoMP PDSCHMap 1100 for BS 102 (the anchor cell, i.e., cell 0), a CoMP PDSCH Map1103 for cell 6 BS, and a CoMP PDSCH Map 1104 for the cell 12 BS. Ineach of the CoMP PDSCH Maps 1100, 1102, 1103, the control region 1105for the CoMP joint processing is sent in the first three OFDM symbols1121, 1122, and 1123 while the CoMP PDSCH region starts from the fourthOFDM symbol 1124. In CRCS3, no REs exist in which a CRS-PDSCH collisioncan occur since the CRSs, R₀ and R₁, are transmitted in the same REs(also referred to as CSREs).

The resource elements mapping for CoMP PDSCH illustrated in FIGS. 7through 11 are transparent schemes where SS 116 does not need to receiveadditional information regarding the CoMP PDSCH resource mapping in thedownlink grant. However, in some embodiments an indication is includedin the downlink grant (such as in possible new DCI formats) to indicatethe possible CRS-PDSCH overlapping pattern of the active CoMP set; andSS 116 can expect to avoid performing demodulation on those overlappedresource elements.

FIG. 12 illustrates frequency shifts for CRS according to embodiments ofthe present disclosure. The embodiment of the frequency shifts shown inFIG. 12 is for illustration only. Other embodiments could be usedwithout departing from the scope of this disclosure.

The CoMP UE, such as SS 116, can receive an explicit indicationregarding which RE's to avoid. The indicator, included in the downlinkgrant, can indicate the possible CRS-PDSCH overlapping patterns and, assuch, expressly indicate which REs to avoid.

For example, for the two CRS and four CRS configurations, for each OFDMsymbol containing a CRS, only two other cell-specific frequency shiftscan exist in that symbol. BS 102 (e.g., the anchor cell) transmits theCRS, R₀ and R₁, in a symbol 1205 as shown. The CRS, R₀ and R₁, aretransmitted by BS 103 in the symbol 1205 using the next correspondingfrequency, shift_1 1210. That is, BS 103 shifts the frequency for theCRS by one frequency unit in the resource map from the anchor cell, BS102. The CRS, R₀ and R₁, are transmitted by BS 101 in the symbol 1205using the next corresponding frequency, shift_2 1215. That is, BS 103shifts the frequency for the CRS by two from the anchor cell, BS 102.

Therefore, from the active CoMP set 155, four possible CRS-PDSCHoverlapping patterns exist: none of the other frequency shifts, possiblefrequency shift_1 1210, possible frequency shift_2 1215, and both of theother possible frequency shifts. Two bits can be used to indicate theoverlapping pattern in the downlink grant. SS 116 can store a possiblebitmap that can be summarized according to Table 2.

TABLE 2 Bitmap of CRS Possible Positions for 2 CRS and 4 CRSConfiguration Bit in the field CRS Position [0 0] Only anchor cell [0 1]Anchor Cell, and Possible frequency shift 2 [1 0] Anchor Cell andPossible frequency shift 1 [1 1] Anchor Cell, Possible frequency shift 1and Possible frequency shift 2

In Table 2, the possible frequency shift_1 1210 can be defined as thesmallest frequency shift value other than anchor cell frequency shiftand possible frequency shift_2 1215 can be defined as the otherfrequency shift value and vice versa. After receiving the downlinkgrant, SS 116 can expect to receive CoMP PDSCH, that is, data 1315, fromthe PDSCH resource elements region, except for the REs 1310 indicatedfrom the bitmap. For example, assume the cell ID of the anchor cell, BS102 is ‘0,’ the expected RE mapping of CoMP PDSCH can be illustrated inFIG. 13 for the case where the CoMP PDSCH region starts from the fourthOFDM symbol 1305.

For the case where only one CRS is configured at each cell, five otherpossible frequency shifts exist. Therefore five bits are used toindicate the possible CRS-PDSCH overlapping patterns as illustrated inFIG. 14.

The bitmap can be formed the same way as the two CRS and four CRS cases,while the ordering of the other possible frequency shifts can be in theincreasing order or decreasing order of mod 6, other than the anchorcell. In this case, the i^(th) bit in the bit field indicates whetherthe possible frequency shift ‘i’ is on or not (‘1’ stands for on and ‘0’stands for off, and vice versa). For example, a ‘1’ in the i^(th) bit inthe bitmap indicates that the SS 116 will not expect to receive CoMPPDSCH (e.g., data) from resource element (k, L) as shown in Equation 3:k=6m+(v+v_(shift)+i)mod6   [Eqn. 3]

L = 0, N_(symb)^(DL) − 3 m = 0, 1, …  , 2 ⋅ N_(RB)^(DL) − 1.

The variables v and v_(shift) define the position in the frequencydomain for the different reference signals where v is given by Equation4:

$\begin{matrix}{v = \left\{ {\begin{matrix}0 & {{{if}\mspace{14mu} L} = 0} \\1 & {{{if}\mspace{14mu} L} \neq 0}\end{matrix}.} \right.} & \left\lbrack {{Eqn}.\mspace{14mu} 4} \right\rbrack\end{matrix}$

The cell-specific frequency shift is given by

v_(shift) = N_(ID)^(cell)mod 6where

N_(ID)^(cell)is the anchor cell ID.

FIG. 15 illustrates a resource element mapping of CoMP PDSCH based onoverlapping patterns according to embodiments of the present disclosure.The embodiment shown in FIG. 15 is for illustration only. Otherembodiments could be used without departing from the scope of thisdisclosure.

For example, when the cell ID of BS 102, e.g., the anchor cell, is ‘0,’the expected RE mapping of CoMP PDSCH can be as illustrated in FIG. 15.In the CoMP PDSCH resource map 1500 for BS 102 (the anchor cell, cell 0)and the CoMP PDSCH resource amp 1501 for BS 103 (cell 1), the CoMP PDSCHregion starts from the fourth OFDM symbols 1524 in one subframe.Further, the bitmap in the DL grant for CoMP PDSCH resource map 1500 is“1 0 1 0 1” and the bitmap for CoMP PDSCH resource map 1501 is “1 1 0 00.” The shaded resource elements (REs) 1510 are the REs where aCRS-PDSCH collision can occur. Accordingly, the shaded REs 1510 arepunctured such that SS 116 is not expecting to receive data 1515 in theshaded REs 1510.

In some embodiments, the CRS-PDSCH overlapping pattern is configuredsemi-statistically. The bitmap of the overlapping pattern can be sent toSS 116 through higher layer signaling semi-statistically. Once SS 116receives the indication, SS 116 will assume certain type of CoMP PDSCHresource mapping for the downlink transmission.

Although the present disclosure has been described with an exemplaryembodiment, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims.

What is claimed is:
 1. For use in a wireless communication network, abase station capable of communicating with a plurality of subscriberstations, the base station comprising: a plurality of antennasconfigured to transmit data and control information; a transmittercoupled to the plurality of antenna, wherein the transmitter isconfigured to transmit a plurality of symbols in a sub-frame to asubscriber station; and a controller configured to include a bitmap in adownlink control information (DCI), wherein the bitmap is configured toinform the subscriber station regarding a subset of cells within, fromamong a coordinated multipoint (CoMP) measurement set of cells, to bemeasured for channel quality information reporting.
 2. The base stationas set forth in claim 1, wherein the bitmap comprises a plurality ofbits that correspond to respective cells of the CoMP measurement set. 3.The base station as set forth in claim 2, wherein the subset of cellswithin the CoMP measurement set includes an anchor cell serving thesubscriber station and wherein the plurality of bits comprises at leasttwo bits configured to identify cells within the subset of cells withinthe CoMP measurement set other than the anchor cell.
 4. For use in awireless communication network, a subscriber station capable ofcommunicating with a plurality of base stations, the subscriber stationcomprising: a plurality of antennas configured to receive data andcontrol information; a receiver coupled to the plurality of antenna,wherein the receiver is configured to receive a plurality of symbolsfrom a Physical Downlink Control Channel (PDCCH) in a subframe from abase station; and a controller configured to interpret a bitmap in adownlink control information (DCI), wherein the bitmap is configured toidentify a subset of cells within, from among a coordinated multipoint(CoMP) measurement set of cells, to be measured for channel qualityinformation reporting.
 5. The subscriber station as set forth in claim4, wherein the bitmap comprises a plurality of bits that correspond torespective cells of the CoMP measurement set.
 6. The subscriber stationas set forth in claim 5, wherein the subset of cells within the CoMPmeasurement set includes an anchor cell serving the subscriber stationand wherein the plurality of bits comprises at least two bits configuredto identify cells within the subset of cells within the CoMP measurementset other than the anchor cell.
 7. For use in a wireless communicationnetwork, a method for communicating with a plurality of subscriberstations, the method comprising: transmitting, to a subscriber station,a plurality of symbols in a sub-frame; and including a bitmap in adownlink control information (DCI), the bitmap configured to inform thesubscriber station regarding a subset of cells within, from among acoordinated multipoint (CoMP) measurement set of cells, to be measuredfor channel quality information reporting.
 8. The method as set forth inclaim 7, wherein the bitmap comprises a plurality of bits thatcorrespond to respective cells of the CoMP measurement set.
 9. Themethod as set forth in claim 8, wherein the subset of cells within theCoMP measurement set includes an anchor cell serving the subscriberstation and wherein the plurality of bits comprises at least two bitsconfigured to identify cells within the subset of cells within the CoMPmeasurement set other than the anchor cell.
 10. A method, comprising:receiving higher layer signaling that provides a set of frequency shiftsfor reference signals (RS), and a downlink control information (DCI)format that includes a field indicating a frequency shift from the setof frequency shifts and scheduling reception of a physical downlinkshared channel (PDSCH) over a set of resource elements (REs), whereinthe set of REs within which the PDSCH is scheduled for receptionexcludes REs corresponding to REs of the RS for the indicated frequencyshift; and extracting data from the PDSCH.
 11. The method of claim 10,wherein the frequency shift corresponds to the respective RS.
 12. Amethod, comprising: transmitting higher layer signaling that provides aset of frequency shifts for reference signals (RS), and a downlinkcontrol information (DCI) format that includes a field indicating afrequency shift from the set of frequency shifts and schedulingreception of a physical downlink shared channel (PDSCH) over a set ofresource elements (REs), wherein the set of REs within which the PDSCHis scheduled for reception excludes REs corresponding to REs of the RSfor the indicated frequency shift; and transmitting data in the PDSCH.13. The method of claim 12, wherein the frequency shift corresponds tothe respective RS.
 14. A base station, comprising: a controller; and atransmitter communicably coupled to the controller, the transmitterconfigured to transmit higher layer signaling that provides a set offrequency shifts for reference signals (RS), and a downlink controlinformation (DCI) format that includes a field indicating a frequencyshift from the set of frequency shifts and scheduling reception of aphysical downlink shared channel (PDSCH) over a set of resource elements(REs), wherein the set of REs within which the PDSCH is scheduled forreception excludes REs corresponding to REs of the RS for the indicatedfrequency shift, and data in the PDSCH.
 15. The base station of claim14, wherein the frequency shift corresponds to the respective RS.
 16. Auser equipment, comprising: a receiver configured to receive higherlayer signaling that provides a set of frequency shifts for referencesignals (RS), and a downlink control information (DCI) including a fieldindicating a frequency shift from the set of frequency shifts andscheduling reception of a physical downlink shared channel (PDSCH) overa set of resource elements (REs), wherein the set of REs within whichthe PDSCH is scheduled for reception excludes REs corresponding to REsof the RS for the indicated frequency shift; and a controller configuredto extract data from the PDSCH.
 17. The user equipment of claim 16,wherein the frequency shift corresponds to the respective RS.